In 1918 Pierrepont married Marie-Louise Roosevelt Butterfield (1889–1984), daughter of Sir Frederick Butterfield of
Cliffe Castle,
Keighley. They had three children: • Mary Helen Venetia Pierrepont (22 May 1920 - 21 February 1930) • Evelyn Louis Butterfield Pierrepont (8 May 1924 - 29 September 1928) •
Lady Frederica Rozelle Ridgway Pierrepont (17 November 1925 - 22 June 2015). Lady Rozelle was an author under the pen name Rozelle Raynes. She married Major Alexander Montgomerie Greaves Beattie in 1953 (divorced 1961) and Richard Hollings Raynes in 1965. She inherited the Pierrepont estates on the death of her father. Marie-Louise, Countess Manvers, was creating art under the name of Marie-Louise Pierrepont. ==Death==